Some contain random gifts, like a Bluetooth speaker, LED lights, or a computer vacuum cleaner.

But now the mystery has taken an X-rated turn, with Amazon confirming that increasingly the items include sex toys.

That's what happened to Nikki. She told The Daily Beast that when she originally received a $25 sex toy in the post she thought there'd been a mix-up. She'd bought some mascara from the shopping site that hadn't arrived yet.

“At first I believed it to be a mistake,” she said. "I looked [the sex toy] up, and it’s $25, which is sort of substantial. It seems so personal.”

In recent weeks, more unwanted packages containing sex toys have been mailed out to strangers

Amazon said that it's investigating.

A spokesperson told The Sun in a statement: "We are investigating inquiries from consumers who have received unsolicited packages as this would violate our policies.

"We have confirmed the sellers involved did not receive names or shipping addresses from Amazon. We remove sellers in violation of our policies, withhold payments, and work with law enforcement to take appropriate action."

Nikki allegedly called Amazon customer service repeatedly to decipher the identity of the sender, with no luck.

Fearing she was being cyber-stalked, she wanted to figure out whether she should get the police involved.

On her first call with Amazon, she claims she had to fight with a representative and supervisor to take her concerns seriously.

“[They were] under the impression that I was simply calling to find out who sent me a fun gift to satisfy my own curiosity,” she told The Daily Beast.

The company told The Sun: "We investigate every report of customers receiving unsolicited packages, and thus far our investigations have shown very few reviews submitted associated with these shipments."

We will continue our ongoing efforts to prevent abuse and will ban all vendors and reviewers who abuse the reviews system."

Massachusetts couple Mike and Kelly Gallivan were inundated with mystery packages from Amazon

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